The present invention relates generally to a closure for drinking receptacles and more particularly to a resiliently biased valve closure for use with a drinking receptacle during intermittent drinking of hot or cold beverages therefrom.
Beverages, such as hot coffee or tea, cold carbonated drinks, beer and the like, are often provided in throw-away or disposable drinking receptacles having substantially impermeable rim-engaging closures which prevent spillage of the beverage and aid in maintaining the temperature of the beverage, whether hot or cold. Such disposable drinking receptacles and closures therefor are typically found in or used in connection with vending machines, business establishements offering carry-out beverage services, to so-called "fast food" restaurants, offices, factories and in many other places where beverages are sold or otherwise provided. Frequently, the consumer will drink intermittently from the receptacle while engaged in other tasks, for example, when he is driving or riding in a vehicle or working at his place of employment. In such situations, the prior art closures for disposable drinking receptacles are generally discarded, in the case of hot beverages and, in the case of cold beverages, a drinking straw is often inserted into a knock-out opening provided in the closure. In either case, however, the likelihood of spillage of the beverage is substantially increased and maintenance of the beverage temperature, particularly hot beverages if the closure is discarded, is adversely affected.
Generally speaking, valve closures for receptacles containing consumable liquids are known in the art, as are the problems associated with maintaining the temperature of the beverages contained in the receptacles. Typical examples of known valved closures are discloed in the following U.S. Patents which were uncovered by a search of the prior art:
U.S. Pat. Nos. 1,066,813; 1,327,389; 1,412,330; 1,592,362; 2,274,844; 2,701,078; 2,780,395; 2,826,345; 2,961,133; 3,059,817; 3,341,088; 3,343,709; 3,871,522; 3,967,748.
The prior art devices described in the patents listed above, as well as other prior art receptable closures have not been completely responsive to the above-discussed problems. In particular, many of the known devices are of rather complex design and, therefore, comparatively expensive construction. Moreover, partly because of their costly construction, these prior art closure devices are notably unsuited for use with disposable drinking receptacles.
U.S. Pat. No. 3,967,748, for example, discloses one type of valved closure used in connection with a thermally insulated double-walled container for hot or cold beverages. The valve closure comprises a cover having a drinking opening therein and a spring-biased valve with an O-ring seat operable by depressing and holding a spring-biased, finger-operated plunger to open the valve and permit drinking from the opening. One difficulty with this device is that the valve must be maintained open by constant finger pressure applied to the plunger which is disadvantageously located well above the center of gravity of the liquid-filled receptacle thus making drinking from the receptacle with only one hand more difficult and awkward. Another disadvantage of this device is that the valving mechanism is positioned on the inner surface of the closure such that it will be at least partly immersed in the beverage when the container is tilted for drinking. Thus, a thorough cleaning of the valve mechanism must be performed for sanitary reasons before the closure can be reused. In addition, this device includes a large number of complex parts, some of which are assembled together by press fitting or cementing so that the valve mechamism cannot be readily disassembled for cleaning.